In my school, we learned of various religions and the basic tennets of them in "area studies" but this was only taught in the gifted track. As is, in my year one kid's parents insisted he be allowed to leave the classroom and sit in the hallway during the discussing of any other religions. My parents were none to pleased to hear that we were learning about muslims and budhists, and this was in 1993. How do you think suburbia would handle in depth teaching in the age or terror alerts?
I think you nailed it yourself when you say that it could teach kids many different religions and let them decide for themselves which, if any, to believe. Many parents who have children are horrified, angered by the source of the education of new religion, and do their best to indoctrinate them back to the "one true faith" much less the parents of kids like myself who gave up religion. If I'd have told my parents while I was in highschool I'd have been kicked out of the house, instead of just becomming dead to them after college. Note that I said "most" and other qualifiers. All of that is based upon my experience, and I know some religions which I greatly respect for their views on tolerance, and non-proselytizing (sp?).